The apelin-APJ system is a relatively new discovery. It has generated interest in part due to it's apparent ability to counteract the renin-angiotensin system, which is frequently overactive in many cardiovascular disease.

Angiotensin has a powerful ability to cause blood vessels constrict and reduces their diameter. One of the actions of apelin is to cause blood vessels to relax and the investigators specifically wish test the hypothesis that apelin will cause blood vessels constricted by angiotensin II to relax.

Using forearm venous occlusion plethysmography angiotensin II will be infused to cause reduction in forearm blood flow. Infusion of apelin and sodium nitroprusside will given and vasodilatation will be assessed. Blood samples for the infused arm and contra-lateral arm will be taken at regular time points to assess local and systemic changes in relevant hormones.

Drug: Apelin infusion

Infusion of up to 10picmol/min will be administered intra-arterially to induce vasoconstriction. Thereafter infusions of apelin (0.1, 1.0, 3.0nmol/min) will be given for 6mins each. During the same study, sodium nitroprusside will given (1.0, 2.0, 4.0 microg/min) for 6mins.

Drug: Sodium nitroprusside infusion

Infusion of up to 150-600picmol/min will be administered intra-arterially to induce vasoconstriction. Thereafter infusions of apelin (0.1, 1.0, 3.0nmol/min) will be given for 6mins each. During the same study, sodium nitroprusside will given (1.0, 2.0, 4.0 microg/min) for 6mins.

Active Comparator: Noradrenaline

Using forearm venous occlusion plethysmography noradrenaline will be infused to cause reduction in forearm blood flow. Infusion of apelin and sodium nitroprusside will given and vasodilatation will be assessed. Blood samples for the infused arm and contra-lateral arm will be taken at regular time points to assess local and systemic changes in relevant hormones.

Drug: Apelin infusion

Infusion of up to 10picmol/min will be administered intra-arterially to induce vasoconstriction. Thereafter infusions of apelin (0.1, 1.0, 3.0nmol/min) will be given for 6mins each. During the same study, sodium nitroprusside will given (1.0, 2.0, 4.0 microg/min) for 6mins.

Drug: Sodium nitroprusside infusion

Infusion of up to 150-600picmol/min will be administered intra-arterially to induce vasoconstriction. Thereafter infusions of apelin (0.1, 1.0, 3.0nmol/min) will be given for 6mins each. During the same study, sodium nitroprusside will given (1.0, 2.0, 4.0 microg/min) for 6mins.

Eligibility

Ages Eligible for Study:

18 Years to 85 Years

Genders Eligible for Study:

Both

Accepts Healthy Volunteers:

Yes

Criteria

Inclusion Criteria:

> 18 years old

Exclusion Criteria:

Lack of informed consent

Age < 18 years,

Current involvement in other research studies,

Systolic blood pressure >190 mmHg or <100 mmHg

Malignant arrhythmias

Renal or hepatic failure

Haemodynamically significant aortic stenosis

Severe or significant co morbidity

Women of childbearing potential.

Any regular medication

Previous history of any cardiovascular disease

Contacts and Locations

Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study.
To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below.
For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00901888